The present invention concerns a detonating device for a secondary explosive charge. It applies notably to high-safety detonation systems including one or more exploding foil igniters used to detonate secondary explosive charges, such as hollow charges, slug- or fragment-generating charges, for example, quasi-simultaneously or respecting a precise timing sequence, which may either be pre-established or programmed during the mission depending on the target to be destroyed.
According to the present state of the art, a high-safety detonating system generally comprises an energy reservoir, an energy commutator, switching control and verification circuits and a detonator. In order to function properly, high-safety detonators require the switching of energies of a few hundred millijoules, even one joule, in a few tens of nanoseconds. In the electric circuits this switching implies currents of several kilo-amperes and applied voltages of several kilo-volts. The switching device in use at present is a gas or vacuum discharger. It allows the flow of several kilo-amperes under several kilo-volts when it is in closed mode, but the changeover from open mode to closed mode involves a switching time which is too long for certain applications. The changeover from open mode to closed mode is made by the activation of a third electrode called the "trigger" and under high voltage, 3 to 4 KV for example. This trigger provokes a disruptive discharge between the main electrodes of the discharger, accompanied by interference due to the phenomenon known as "jitters". These "jitters" delay the establishment of the closed mode and provoke switching times generally longer than 100 ns. The times obtained with gas or vacuum dischargers and the jitter phenomenon are incompatible with sequenced or synchronized multipoint initiation systems which require perfect control of the timing and the jitters, and also switching times of the order of a few nanoseconds.
In order to improve the timing precision between the different detonations, and in fact reduce the switching times, one solution consists in using the optical energy of a pulsed laser to trigger the energy switching through the discharger. This method of triggering has been widely described in the following publications: V. A. VUYLSTEKI JAP 34, 1615 (1963), L. L. STEINMETZ, The Review of Scientific Instrument, 39, n.degree.6 (1968), pages 904/909, H. C. HARGES Texas University Report n.degree.LLL 2257509-1 (1979), R. A. DOUGAL et al., J. Phys D.Appli. Phy., 17 (1984), pages 903/918.
The main drawback of the discharger triggered by an optical pulse is that it requires a high power pulsed laser, for example between 100 kW and 1 MW corresponding to energies of between 1 and 10 millijoules transmitted in approximately 10 ns, each discharger having an associated laser which is specific to it.
Today, the most compact laser sources known, whose volumes are of a few tens of cubic centimeters, limit the functioning ranges to a frequency of around 1 kHz and so do not allow rapid sequenced triggering, for example sequences with 100 ns between each pulse. What is more, the powers used for triggering dischargers, notably those of more than 100 kW, impose the use of special wide optical fibers for certain system structures, which are fragile and difficult to use due to the limited curvature they can tolerate without breaking.